By William HarwoodSpecial to The Washington PostTuesday, January 8, 2002; Page A03

Ground-based telescopes equipped with computer-controlled, flexible
mirrors to counteract the blurring turbulence of Earth's atmosphere are on
the verge of being able to photograph large planets orbiting nearby
sun-like stars, astronomers reported yesterday.

While about 80 extra-solar planets have been discovered using indirect
techniques -- measuring the effects of an unseen planet's gravity on the
parent star, for example -- no one has directly made an image of a planet
orbiting another sun.

But two discoveries reported yesterday at the winter meeting of the
American Astronomical Society here indicate the rapidly maturing
technology known as adaptive optics almost certainly will allow
ground-based astronomers to do just that in a few years, if not
sooner.

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"It's technically now possible to directly image a young Jupiter around
a nearby young star," said Ray Jayawardhana, an astronomer at the
University of California at Berkeley. "We have not directly imaged a young
planet yet. . . . But it could very well happen in the next few years, so
keep your eyes and ears open."

With adaptive optics, a thin secondary mirror is precisely flexed many
times per second under computer control so it can largely reverse the
effects of atmospheric turbulence on light entering the telescope. The
result is a much sharper image.

Jayawardhana and his colleagues used an adaptive optics system
developed by the University of Hawaii and the eight-meter Gemini North
telescope atop Mauna Kea to photograph what appeared to be a young double,
or binary, star system in a small cluster of stars 900 light-years
away.

The resulting image shows that one of the blurred "stars" in earlier
ground-based photographs is actually two stars. A longer exposure shows
yet another object near the freshly resolved pair of suns.

Remarkably, an adaptive optics close-up of the elongated object shows
it to be an edge-on "proto-planetary disk" -- a flattened cloud of dust
obscuring the parent star at the center of the disk. Reflected light from
the star illuminates the object.

The stars making up this quadruple star system, and others in the
cluster known as MBM 12, are thought to be about 2 million years old. The
flattened disk indicates the process of planet-building is underway.

Using adaptive optics to obtain images of a broad range of young stars,
astronomers hope to capture such disks in various stages of evolution,
Jayawardhana said, "from the very beginning until it becomes a fully grown
planetary system, to try to understand how long it takes, what processes
are at work and whether it could happen anywhere and everywhere."

All of this leads to direct images of Jupiter-class planets from the
ground -- no small feat when one considers that Earth's sun, when viewed
across interstellar space in infrared light, would outshine Jupiter by
about a billion to one. The trick is finding the planet in the glare of
its sun.

"But a young Jupiter, because it's just formed and it's still hot and
it's still contracting and actually emitting its own thermal radiation,
would only be a hundred thousand times fainter than the young sun,"
Jayawardhana said.

"That may not seem like much of a gain to you, but it's 10,000 times
brighter than an old Jupiter," he said. "And that is enough, already, for
current adaptive optics systems on 10-meter-class telescopes to directly
image a young planet."

Another team of researchers led by Michael Liu of the University of
Hawaii provided a remarkable glimpse of the current state of the art --
and another glimpse of things to come -- in a related discovery.

Liu and his colleagues used adaptive optics with Gemini North and the
huge, 10-meter Keck II telescope atop Mauna Kea to photograph a brown
dwarf orbiting a sun-like star 58 light-years from Earth near an
astronomical formation called the Summer Triangle.

Brown dwarfs are objects between 15 and 80 times the mass of Jupiter,
not massive enough to trigger nuclear fusion in their cores. The brown
dwarf discovered by Liu and company is thought to be about 65 times as
massive as Jupiter.

It orbits its parent star at a distance of just 1.3 billion miles or
so. In Earth's solar system, that would put it roughly midway between
Saturn and Uranus. That's the smallest separation between a star and a
"sub-stellar" object yet photographed, a feat made possible by adaptive
optics.

Alan Boss, a leading planetary theorist at the Carnegie Institution,
called the two discoveries "a very tantalizing appetizer for what's to
come."

"They've now demonstrated they have the ability to" photograph
Jupiter-class planets, he said. "There are several candidates out there --
it's just a question of time."